Ordered length vs available stock length: how to manage cutting and yield

A project may require:

• 3.3 m pipe pieces;
• 6.15 m round bars;
• 11.8 m beams;
• 2.0 m threaded micropile tubes.

The stockholder may have only 6 m, 12 m or mixed random lengths.

The procurement problem is therefore not only:

"Is the section in stock?"

It is:

"Can the available master lengths be converted into the required pieces with acceptable yield, tolerance, traceability and cost?"

Start with three separate values

Keep these separate:

1. Required finished length
2. Available mother/master length
3. Cutting allowance / end loss

Do not assume a nominal 12 m stock length can always produce exactly four 3.0 m finished pieces. Saw kerf, crop ends, damaged ends or squaring allowance can make the arithmetic impossible.

Basic cutting yield

For one repeated finished length, a first-pass estimate is:

Pieces per master = floor(usable master length / required cut length)

Then:

Used length = pieces × required cut length

Residual length = usable master length − used length

This is only a planning calculation. Actual cutting must also include kerf and any required end trim/tolerance.

Example: 3.3 m pieces from 12 m stock

Ignoring kerf for the first pass:

• 3 pieces use 9.9 m;
• approximately 2.1 m remains.

A fourth 3.3 m piece cannot be obtained.

If the project needs 89 pieces, the buyer should calculate how many 12 m master lengths are needed and what happens to the offcuts.

The offcut may be:

• scrap;
• usable for another line item;
• retained by the stockholder;
• purchased by the customer.

That commercial treatment should be clear.

Cutting yield is not only a percentage

A high theoretical yield can still be a poor procurement solution.

Consider:

• whether offcuts match another item;
• stockholder cutting charge;
• minimum billable length;
• re-marking/traceability;
• certification;
• transport limits;
• required end preparation;
• testing coupons.

For expensive duplex or special alloy material, an extra 2% yield improvement can be significant. For commodity beams, delivery speed may matter more.

Multiple required lengths: use nesting

When an MTO has several cut lengths in the same grade/section, optimize them together.

For example, one 12 m bar could potentially be allocated to a combination such as:

• one 6.15 m piece;
• one 3.30 m piece;
• remaining allowance/offcut.

The best pattern depends on kerf and tolerances.

This is a classic cutting-stock / nesting problem. For large MTOs, software or an optimizer can reduce scrap substantially.

Do not lose MTO traceability during optimization

Commercial aggregation must not erase project line identity.

Maintain a mapping such as:

Master bar 004 → MTO item 12 / piece A + MTO item 18 / piece C

This is especially useful where:

• different tags are required;
• different systems/areas use the same size;
• piece marking must show item numbers;
• the buyer requires piece-level material traceability.

See How to turn an MTO into a clean steel procurement list.

Stock length can affect quantity

A client may state total metres while the stockholder sells full bars.

Suppose the project needs 100 m, but the stockholder sells only 12 m bars.

The purchase quantity becomes at least nine bars = 108 m before considering cutting pattern and unusable remnants.

Do not quote exactly 100 m of procurement cost unless the supplier has actually agreed to charge only for the finished pieces.

Random length vs fixed length

Some products are commercially offered in:

• fixed length;
• multiple length;
• random length;
• mill length;
• stock length.

These terms need to be understood in the context of the applicable product standard and quotation.

If the project needs exact fabricated pieces, a generic "random length" offer is not automatically acceptable.

Mill production can solve a bad stock-yield problem

If the quantity is large enough, a mill may produce a more suitable ordered length.

This can:

• reduce scrap;
• reduce cutting;
• simplify traceability;
• lower per-piece handling cost.

But it can also introduce MOQ and lead time.

See MOQ, rolling campaigns and lead time in mill orders.

Remember test pieces and end losses

Projects can require material for:

• destructive tests;
• witness samples;
• production qualification;
• thread trials;
• machining;
• weld coupons.

If these are cut from ordered stock, include them in the yield calculation.

Likewise, pipe ends may require removal before beveling or threading.

Who owns the offcut?

This should not remain implicit.

Possible commercial arrangements:

• customer buys full master lengths and owns all remnants;
• customer buys only finished pieces and stockholder retains scrap;
• scrap value is credited;
• remnants are retained for later project calls.

This can materially change the effective €/kg or €/piece price.

Traceability after cutting

When one master item becomes several pieces, identification must follow the pieces.

Before accepting the cutting plan, confirm:

• marking transfer;
• piece IDs;
• cut map;
• MTC linkage;
• treatment of unmarked remnants.

See Traceability when stockholders cut material from master lengths or plates.

Procurement takeaway

The cheapest mother length is not always the cheapest finished solution.

Compare:

material cost + scrap + cutting + handling + traceability + delivery time

and optimize the actual pieces the project needs.

References and verification sources

• This article is primarily a procurement and cutting-yield guide. Exact length tolerances, random/fixed-length definitions and permissible delivery lengths are product-standard specific and should be checked against the governing product standard and supplier quotation.